The Experimental Research Of Making Bricks By Chrome Sludge

In this paper, a process of making bricks by chrome sludge was proposed. At first,the influences of the chrome sludge content, coal content, holding time, moldingpressure and sintering temperature on the physical properties of bricks were investigated.Then, the influences of chrome sludge content, leaching time and holding time on Cr6+leaching concentration and the total Cr were studied. Moreover, the solidification effectsof different additives such as Fe2O3, fly ash and gangue on Cr6+concentration werecompared. Finally, the field test was carried out on the basis of the optimal ratio andexperimental conditions obtained in the laboratory experiment. The main conclusionsare as follows:With the increase of chrome sludge content from0to12%, the physical propertiesof bricks are decreased gradually. At the same time, the optimal holding time andmolding pressure are4h and20MPa, respectively. The physical properties of bricks areimproved when the sintering temperature varies from800℃to900℃. However, thequality of bricks are not increased when the temperature is above950℃. The increaseof coal content has a negative effect on the physical properties of bricks.When the leaching time is changed from7to30d, the Cr6+concentration and thetotal Cr would be increased. However, the leaching time is increased to45d, the Cr6+concentration and total Cr would be constant. Meanwhile, the Cr6+concentration andtotal Cr would be improved with the increase of chrome sludge. Moreover, the Cr6+concentration and the total Cr were the lowest when the holding time was4h.The optimal physical properties and the lowest Cr6+and total chromium were alsoinvestigated when the additive such as3%Fe2O3,5%fly ash or2%gangue were added.Comparing their physical properties, the bricks with3%Fe2O3and2%gangue have theequal physical properties, but the bricks with2%gangue addition have lower Cr6+andtotal Cr concentration.According to the optimal conditions and ratios, the field test of making brick bychrome sludge was carried out, and the physical properties and Cr6+and total Crconcentration of bricks can reach the standard of current act.